Cystitis in women of child-bearing age

These are the responses and a discussion of this case quiz – Dysuria in an adult woman

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Dysuria and frequency resulting from acute cystitis in women of child-bearing age is a very common reason for primary care visit. This type of urinary tract infection (UTI) is commonly referred to as “uncomplicated” to distinguish it from all other types of UTIs that all get the designation “complicated”. I can’t think of a more stupid classification system. But more on that in other posts…

One would think that this common, easily diagnosed condition would be managed very similarly by all physicians. It isn’t. There is large variance in history taking, physical examination practices, selection of laboratory tests, interpretation of laboratory tests, selection of empiric antibiotic and duration of therapy.

An office visit for this complaint should not take long but there are important elements to consider.

History

One very important distinction is between cystitis alone and cystitis accompanied by pyelonephritis. Questions aimed at differentiation might include “Have you had a fever and if so have you measured it?” “Have you had any pain in your back?” People with pyelonephritis are generally systemically unwell whereas people with cystitis are not.

Another consideration is the possibility of urethritis causing dysuria and frequency. Questions aimed at determining the possibility of STIs may be indicated.

Pregnancy is important to rule out as management is different in pregnancy.

Physical Exam

Exam should be limited in most cases of acute cystitis. Measurement of temperature is always prudent and it is good practice to instruct office staff to take the temperature of patients with potential infection-related symptoms when placing them in the examining room.

Always look for costo-vertebral angle tenderness by gentle tapping with the closed fist. Pelvic exam should be reserved for those in which there is considerable suspicion of STI.

Laboratory

A dipstick urinalysis (or other laboratory performed urinalysis if quickly available) is always indicated. A negative urinalysis should increase the suspicion of urethritis potentially caused by STI. Leukocytes, blood and nitrites are the analytes of interest. Inflammation is associated with leukocytes, while nitrites are present if there are bacteria from the family Enterobacteriaciae present. As E. coli is, by far, the most common bacterium causing UTI, many UTIs are manifest by nitrites present on urinalysis. However, other organisms (most notably Enterococci) can cause UTI and do not reduce nitrates to nitrites and therefore the nitrite test will be negative.

There is no broad consensus concerning the advisability of urine culture in this setting. Many experts (like me) believe that, because empiric therapy is indicated and effective in the large majority of patients, culture is not indicated. Culture is relatively expensive the the result is quite unlikely to influence the care. All people who fail empiric therapy should have cultures, of course.

Nitrofurantoin is now preferred empiric therapy

Recently, in part because of increases in resistance rates to trimethoprim-sulfamethoxazole and fluoroquinolones, and in part to reserve fluoroquinolones and cephalosporins for more serious hospital-associated infections, nitrofurantoin has become the Drug of Choice. Though slightly more expensive, the monohydrate/macrocrystals formulation (Macrobid TM) is preferable as it is dosed 100 mg BID. The other available form (Macrodantin TM) is macrocrystals only is dosed 50-100 mg QID. Specify Macrobid when prescribing. Duration of therapy is 5 days for either formulation.

Despite being used for many years, resistance is still rare in E. coli and many strains of enterococci are also susceptible. It cannot be used for pyelonephritis and caution must be used in patients with renal dysfunction. See http://infectionnet.org/questions/nitrofurantoin-safety-in-the-elderly/

Alternate agents include Trimethoprim-sulfamethoxazole 1 DS tablet BID x 3 days, cefixime 400 mg OD x 3 days or ciprofloxacin 250 mg BID or 500 mg XL form OD x 3 days.

Another new alternative (actually the re-appearance of an old drug) is fosfomycin. Fosfomycin is given as a single dose of 3 grams in powdered form mixed with water. I will write a post about fosfomycin soon.